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Placebo effect
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Placebo effect
Summary
A placebo is any medical treatment that is inert (inactive), such as a
sugar pill. Around one third of people who take placebos (believing
them to be medication) will experience an end to their symptoms. This
is called the placebo effect.
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Placebo is Latin for 'I will please', and refers to any medical
treatment that is inert. The placebo has long been used in research
trials to objectively test the efficacy of a new health care treatment,
such as a drug. A placebo is indispensable to the conduct of many
scientifically-based clinical trials. Ethical considerations require
that participants in clinical trials be told that they may be given a
'dummy' treatment.
Usually, one group of people takes the drug while another group (the
control group) takes the placebo. The placebo may be a sugar pill. None
of the participants know whether they are taking the active or inactive
substance. Sometimes, not even the researchers know (double blind
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Comparing the results from both groups should indicate the effects of
the drug. However, people sometimes get better when they are taking a
placebo. This phenomenon is known as 'the placebo effect'. Estimates
vary, but around one third of people taking placebos for complaints
(including pain, headache and seasickness) will experience relief from
symptoms. There are various theories that attempt to explain this
phenomenon but the underlying mechanisms remain mysterious.
Types of placebos
A placebo doesn't have to be a pill. It can be any inert or 'dummy'
treatment, such as special diets, exercise, physical therapy or even
surgery. The placebo effect is triggered by the person's belief in the
treatment and their expectation of feeling better, rather than the
specific form the placebo takes.
The misconception of 'imaginary' disorders
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Influencing factors
Some of the factors that influence the placebo effect include:
* The characteristics of the placebo - if the pill looks genuine, the
person taking it is more likely to believe that it contains
medicine. Research shows that larger sized pills suggest a stronger
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powerful effect than pills.
* The person's attitude - if the person expects the treatment to
work, the chances of a placebo effect are higher. Some studies show
that the placebo effect may still take place even if the person is
sceptical of success. The power of suggestion may be at work here.
* Doctor-patient relationship - if the person trusts their health
care practitioner, they are more likely to believe that the placebo
will work.
How placebos work
The exact physiological mechanisms remain mysterious. Some of the
theories that attempt to explain the placebo effect include:
* Self-limiting disorders - many conditions, such as the common cold,
are self-limiting. They will resolve by themselves anyway, with or
without placebos or drugs, and the end of symptoms is merely
coincidence.
* Remission - the symptoms of some disorders, such as multiple
sclerosis and lupus, may wax and wane. A remission during a course
of placebos may be coincidence, and not due to the placebos at all.
* A change in behaviour - the placebo may increase a person's
motivation to take better care of themselves. Improved diet,
regular exercise or rest may be responsible for the easing of their
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may change with the expectation of feeling better. For example, a
sharp pain may be reinterpreted as an uncomfortable tingling.
* Reduced anxiety - taking the placebo and expecting to feel better
may soothe the autonomic nervous system and reduce the levels of
stress chemicals, such as adrenaline.
* Brain chemicals - placebos may trigger the release of the body's
own natural painkillers, the brain chemicals (neurotransmitters)
known as endorphins.
* Altered brain state - research indicates that the brain responds to
an imagined scene in much the same way as it responds to an actual
visualised scene. A placebo may help the brain to remember a time
before the onset of symptoms, and then bring about physiological
change. This theory is called 'remembered wellness'.
The argument against placebos
Placebos have the power to cause unwanted side effects. Nausea,
drowsiness and allergic reactions, such as skin rashes, have been
reported as placebo effects. Critics of placebos maintain that
deception is wrong, regardless of whether the deceived patient
experiences an end to their symptoms. The longterm prescription of
placebos by an unscrupulous health care practitioner may also convince
an otherwise healthy person that they are suffering from an illness or
infection that requires ongoing treatment. The mind-set of believing
oneself to be ill may contribute to the onset of genuine symptoms. A
good doctor-patient relationship with good communication is usually
preferable to the use of a placebo.
The placebo effect is doubted by some
Some researchers doubt the placebo effect even exists. For example,
medical philosophers at the University of Copenhagen recently analysed
trials that involved placebos and declared that placebos offered about
the same degree of symptom relief as no medical treatment. Critics
point out that the methodology used by the medical philosophers was
flawed, and that the placebo effect has been well documented for many
years.
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Things to remember
* A placebo is any medical treatment that is inert, such as a sugar
pill.
* Around one third of people who take placebos (believing them to be
medication) will experience an end to their symptoms.
* Belief in a treatment may be enough to change the course of a
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Placebo effect - Better Health
Channel
A placebo is any medical treatment that is inert (inactive), such
as a sugar pill. Around one third of people who take placebos
(believing them to be medication) will experience an end to their
symptoms. This is called the placebo effect.
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